Labor leaders Thursday said “hundreds” of low-wage workers at Chicago’s O’Hare International Airport have voted to strike, and warned that those employees may not show up during the busy holiday travel season.

The vote was taken among an estimated 2,000 non-unionized workers who have been attempting to organize with the help of Service Employees International Union, SEIU Local 1 President Tom Balanoff said at a news conference at the union’s headquarters.

The employees, who work mostly for private contractors at the airport in jobs such as baggage-handling, security, catering and cleaning, are protesting retaliation against union organizers and workplace grievances such as unpaid overtime and unsafe working condition. The workers also hope to see wages at the airport boosted to a minimum of $15 per hour.

The Chicago Department of Aviation is “committed to ongoing dialogue with all parties” and does not expect to see any disruption to service during the holidays, a spokesman said.

The Aviation Department “expects every contractor to follow the law, and will aid the Chicago Department of Business Affairs and Consumer Protection and the Illinois Department of Labor to take whatever action is necessary,” spokesman Owen Kilmer said. “We do not anticipate any disruption in service at Chicago’s airports during the holiday season and encourage passengers to contact individual airlines for information regarding their specific flight.”

Balanoff would not say how many workers had joined the vote — calling it an “overwhelming majority” of those asked to vote — but said the number was great enough that a walk-out could slow, but not shut down, operations at the world’s fourth-busiest airport.

“They don’t expect to shut the airport down. That’s not what they’re trying to do. Oh, there will be disruption,” Balanoff said to cheers from and audience that included Ald. Scott Waguespack (32nd), and Ald. George Cardenas (12th). What “they’re trying to do is get the powers that be to hear their voice.”

Airport workers surveyed for the strike vote were, on average, older than 30. Most make less than $12 an hour.

Oliwia Pac, 24, has worked at the airport for more than three years, pushing passengers in wheelchairs, standing watch on security or attending to unescorted minors. She said her employer frequently shorts her on wages — each of her duties pays at a different rate, ranging from $8.25 to $11.50 — and she injured her wrist pushing two wheelchairs at the same time, a practice that she called commonplace but which violates labor laws.

“I definitely think a lot of people will strike if it comes to that,” Pac said. “I really think people are sick and tired.”